Control system



July 29, 1930.

A. PINTO CONTROL SYSTEM Original Filed April 2, 1926 2 Sheets-Sheer. l.

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CONTROL SYSTEM original FiledApril 1926 2 sheets-sheer 2 m2 FIGB wwwFidi' mvenron l BY ArToRNEY Patented July 29, 1930 UNlTEDsTATl-:s

PATENT OFFICE ANTHONY PINTO, OFNEW YORK, N..Y., ASSIGNOR TO OTISELEVATOB COMPANY, 0F JERSEY CITY, NEW JERSEY, A CORPORATION OF NEWJERSEY coN'raor. SYSTEM OriginalA application led pril'2, 1926, SerialNo. 99,259. Divided and this application filed October 7, 1927. SerialNo. 224,652.

The invention relates to control systems, and particularly to controlsystems for elevators. y

This application is a division of apphcation Serial No. 99,259, liledApril 2, 1926.

As theart of elevators has developed, various improvements have greatlyincreased the efficiency of operation of the elevator systems over thoseof the earliest types. Among these improvements have been those designedto reduce the time required to etfect the completion of certainoperations. One operation in which time is an important factor,particularly in high speed elevator systems, is that of bringing the carto a stop at the landings. Where time is lost in making each stop, itwill be seen, upon consideration of the total timelost during a daysoperation or even during a single round trip, that the operatinefficiency of the system as a whole is consi erably impaired.Self-leveling mechanism, which has been provided in many elevatorsystems in recent years for bringing the car to a level withthe desiredlanding in stopping, regardless of whether it underruns or overruns thelanding, has for `one of its features a reduction inthe time required tobring the car to an accurate stop at the landing. a

Vhere self-leveling apparatus isemployed in elavator systems wherein adirect current electric motor is used for raising and lowering the carand wherein power is supplied to the motor from a direct currentvariable voltage generator, the control of the field strength of thegenerator must be such that the E. M. F.

generated may be rapidly brought to the desired values for obtaining thevarious leveling operations. Upon the occurrence. ot' an overrun in suchsystems, it is advantageous to reverse thel polarity of the E. M. F.generated to effect the return of the car to the landing. This is truealso in systems wherein the leveling apparatus is omitted, such as thosein which the stopping operation is automatic and which are arranged forinching the car back to the floor in the, event that it has run past andthose in which the starting, stopping and reversal ofthe car is undermanual control. Furthermore, the reversal of the generator E. M. F. isadvantageous' for ei'ecting a reversal in the direction of movement ofthe car at any point in the hatchway. Considerable time may be lost ineffecting the reversal of the generator E. M. F.,however, due to thetime constant of the generator field.

i One feature of the present invention resides in minimizing the timerequired to bring the generato-1' E. M. F. from a certain value of onepolarity to a certain value of the other polarity. v

AOther features and advantages will become apparent from the followingdescription and appended claims. f e

The invention will be described, by way of illustration, as embodied ina system in which both the starting and stopping of the car under thecontrol of an operator. It is to be understood, however, that it is alsoapplicable to other elevator systems, such as those in which push buttoncontrol is employed for causing both the starting and stopping of thecar or for causing only the stopping of the car, or those in which thestarting ot the car is under the control of an operator while the slowdown and stopping is automatic. Furthermore, the system in which theinvention is embodied will be described, also by way of illustration, asprovided with selfleveling mechanism, with the invention applied to theleveling operations. It is to be further understood, however, that theinvention is adaptedr for use in other operations, such as the operationof reversing the car at any point and is applicable to systems in whichself-leveling apparatus is not employed, such as those in which theaccuracy o1"- the stop is made de pendent upon the skillr of theoperator and in which, in the event oi' an overrun, the return to thefloor is caused by inching, or to those in which the car is caused tostopfauxomatically at the landing and in which means are provided forinching the car back to the ioor in the event oitr an overrun.

The invention involves thepolarity of one portion of the generatorseparately excited field winding being reversed with respect to that ofanother portion. This cau-ses the magnetizing forces of these portionsto act in 0p position. Then by varying the magnetizing force of eitheror each of said portions, the net magnetizing force of the winding maybe caused to be such that an E. M. F. of either polarity may beobtained, the particular polarity depending upon which one of saidportions predominates.

In carrying out the invention, according to the preferred arrangement,certain connections in the generator separately excited field windingcircuit are changed for the leveling operation so as to cause thecurrent in a porA tion of the field winding to flow in a reverseddirection with the direction of the flow of current through theremainder of' the winding remaining the same. Upon an underrun, thecurrent flowing through said portion is caused to be less than thatflowing through the rcmainder of the winding with the result that an M.F. of proper polarity is generated. Upon an overrun, in order to reversethe polarity of the E. M. F. generated so as to effect the return of thecarto the landing, the direction of the flow of current through thewhole winding is not ieversed but the current flowing through saidportion is caused to be greater than that flowing through the reAmainder of the winding.

Other conditions arise, where a variable voltage direct currentgenerator is. employed to supply power to the elevator motor, which tendto cause variations in operation during the leveling period. During thisperiod, the generator is required to operate at low values of' E. M. F.in order to obtain satisfactory operation for bringing the car to alevel with a landing. Due to the residual flux of the genT erator field,assuming the generator sepa.-

rately excited field winding connected the.

same for leveling as for operation between floors, the E. M. F, valuesobtained vfor ay given value of field current during the. levelingperiod vary considerably, depending onthe magnetic state of the machineprior t-o level'- ing and whether the car is'. being broughtto.

the landing upon an underrun or returned to the landing after anoverrun. Such variations in E. M. F. values cause undesirable variationsin the operation of the car during the leveling period. The preferredarrangement of the invention also obviates the eliects of the residualflux of the generator and thereby causes more uniform operation dur ingthe leveling period. I

A system of control directed to similar subject matter is shownin thisinventor"s copending application, Serial No. 60,769, filed October 6,1925, and division thereof, Serial No. 273,290, filed April 27, 1928.

In the drawings.:

Figure 1 is a diagram of an elevator control svstem embodying theinvention;

y Figure 2 is a fragmental schematic view of a `portion of the elevatorsystem, lllustrating particularly the manner 1n which the generatorfield winding is controlled during the leveling operation; and

Figure 3 is a hysteresis curve employed to illustrate the invention.

No attempt is made in Figure 1 to show the coils and contacts of thevarious electromagnetic switches in their associated positions, astraight diagram being employed wherein the coils and contacts of thevarious switches are separated in such manner as to render the .f

circuits involved relatively simple. Also the parts of other switchesand apparatus are separated in the interest of simplifying the diagram.For a clearer understanding of the invention, the stationary contacts ofthe I switches are illustrated in cross section.

The motor generator set comprises a driving motor 11, illustrated forconvenience of description as of the direct current type, and a variablevoltage direct current generator 12. The armature of the driving motoris designated 13 and its field winding 14. The armature ofthe generatoris designated 15, its series field winding 16, its separately excitedfield winding being divided into two portions 17 and 18. The elevatormotor is designated as a whole by the numeral 20, its armature beingdesignated 21 and its field winding An adjustable resistance 23 isarranged in shunt to the generator series field winding. Dischargeresistances 24 and 25 are provided for the portions 17 and 18respectively of the generator separately excited field winding.Discharge resistance 26 is provided for the elevator motor fieldwinding. A. resistance 27 is provided for controlling the strength ofthe generator field and therefore the voltage applied to the elevatormotor armature. A resistancey 28 is provided for controlling therelative values of the current supplied to the generator field windingportions 17 and 18 during leveling. 30 is the release coil for theelevator motor electromagnetic brake. This coil is provided withdischarge resistance 31 for controlling the application of the brakeduring the stopping operation. 32 and 33 are the up slow speed contactsand the down slow speed contacts respectively of the leveling switch,the up and down fast speed leveling switch contacts being designated 34and 35 respectively. 36 is the armature and 3T is the field winding ofthe motor 38 for moving the rollers of the leveling switch into positionto clear the leveling cams. 40 and 41 are the direct current supplymains. 42 is a double pole knife switch for connecting the system to thesupply mains. In order to suit the type of' diagram employed, the bladesof this switch are shown separated. The car switch is designated as awhole by the numeral 43. 41 is the safety switch in the car. The varioussafety, limit, stop and emergency switches anddoor and gate contacts areomitted in order to simplify the description.

The electromagnetic switches have been designated as follows: y

A--potential switch,

B-up direction switch,

C-down direction switch,

F-v-accelerating switch,

(ir-maintaining relay, H-brake switch,

L-'field control switch, l

' M-series field relay,

N--series field switch,

P-leveling switch motor relay,

LU--up leveling direction switch,

-LD-down leveling direction switch,

LR-field control leveling relay,

LIL-fast speed leveling relay,

LI-intermediate speed leveling relay.

- Throughout the description which follows, these letters, in additionto the usual reference numerals, will be applied to the parts oftheabove enumerated switches.` For example, contacts B 66 are contacts onthe up direction. switch, while actuating coil A is the coil thatoperates the potential switch.' The electromagnetic switches are shownin their deenergized positiona/ Inductance coil are similarly designatedby the characterk f Upon the closing of the knife switch 42, the drivingmotor 11elevat0r motor field Winding 22 and potential switch actuatingcoil A 45 are energized, the circuit for coil A 45 being by way of line46including safety switchv 44. The driving motor starts in. operation,bringing the generator 12 up to full speed. Starting means for thedriving motor are omitted to simplifythe description. The potentialswitch, upon operation, causes the engagement ofcontacts A and A 51preparing the circuits for the generator separately excited fieldwinding and the electromagnetic brake release coil and also the controlcircuits. The condition of the circuits sok far described might betermednormal.

`Assume that the system is designed for an installation of severalfloors and that the carv is at rest. atthe first floor landing. In orderto, start the car in the up direction, the operator moves the car switchinto position where its contact kbar 52bridges contacts 53, 54, 55 and56. Uponthe contact bar 52 engaging contact 54, a circuit is completedfor the actuation coil B 57 of the up direction switch and the actuatingcoil H 58 of the brake switch. This circuit may betraced from theleft-hand blade ofk switch 42, by Way of line 79 through contactsA 50,by way of line 60 through coils H 58 and B 57, contacts 54 and 53 oftheA car switch. by way of line 61 through contacts C 62, line 63,switch 44, line 46, by way of line 89, to the right-hand blade of switch42. The engagement of the contact bar 52 and contact 55 prepares acircuit for the `actuating coil F 830i the accelerating switch. Theengagement of the It is preferred to provide the direction switches witha mechanical interlock to prez vent their simultaneous operation. Suchan interlock may be of the form of a walking beam pivotally mounted forengaging i n catches on the armatures of the direction switches. Uponoperation of the up direction switch in response to the energization ofits actuating coil B 57, contacts B 65 separate and contacts B 66, B 67and B 68 engage. The separation of contacts B 65 breaks the circuitleading from the car switch down feed contact 70, contacts B 65 and thecorresponding down direction switch contacts C 62 serving as electricalinterlocks. The engagementof` contacts B 68 prepares the circuit for theup direction switch holding coil B 71 and the brake switch holding coilH 72. The engagement of contacts B 66 and B 67 coninletes a circuit forthe generator separately excited field winding. This circuit may betraced from the left-hand blade of switch 42, by way of line 79 throughcontacts A 50 and resistance 27, by way of line 73 through contacts B66, by way of line 74, through field control switch contacts L 120,field winding portion 18, by way of line 121 through contacts L 122,field winding portion 17 and actuating coil G 75 of the maintainingrelay, by way of line 89 through contacts 67 and contacts A 51, to therighthand blade of switch 42. Relay G does not operate at this time asinsufficient current is supplied to its actuating coil.

The brake switch H operates simultaneously with the direction switch B.Switch H, upon operation, causes the separation of contacts H 77 and theengagement of contacts H 80 and H 81. The separation of contacts H. 77disconnects the generator separately excited field winding from thegenerator armature. The purpose of contacts H 77 will be seen from laterdescription. The engagement of contacts H 8O completes the circuit forthe brake release coil 30. This circuit may be traced from the left-handblade of switch 42, by way of line 79 through contacts A 50, by way ofline 82 through coil 30 and contacts H 80, by way of line 89 throughcontacts A 51, to the right-hand blade of switch 42. The engagement ofcontacts H 81 completes the circuit for the accelerating switchactuating coil F 83. This circuit may be traced from the left-hand bladeof switch 42, by way of line 7 9 through contacts A 50, by way of line84 through contacts H 81, contacts L 47, inductance coil X 85 and coil F83,

contacts and 53 of the car switch, by way ci line 61 through contacts C62, line 63, switch le, line 16, line 89, to the right-hand blade ofswitch 42.

The leveling switch motor relay, upon operation, causes the engagementof contacts P 98, completing the circuit for the leveling switch motor88. This circuit may be traced from the left-hand blade of switch 42, byway of line T9 through contacts A 50, by way o1 line 9-1 througharmature 86 and field winding 8T ot' motor 88 and contacts P 98, by wayot line 89 through contacts A 51., to the right-hand blade or" switch42. The leveling switch motor acts to move the leveling switch operatingrollers so as to clear the leveling cams during the movement of the car.This operation will be explained later.

The brake release coil being energized and current being' Supplied fromthe generator armature 15 to the elevator' motor armaturc 2l, due to thegenerator' lield winding portions 1T and 18 being energized, theelevator motor starts. The lield winding portions 1T and 18 as nowconnected assist each other.

The accelerating switch F docs not operate immediately the circuit forits actuating coil F 83 iscompleted, its action being delayed by theinductance coil X 85. Upon operation, switch F causes the separation ofcontacts F 8T and the engagement of contacts F 88 and F 90. Theseparation oi contacts F 8T removes the short-circuit around the holdingcoil P 91 of the leveling switch motor relay. The engagement ot contactsF 88 completes the circuit for holding coils B 71, P 9'l'and H T2. Thiscircuit may be traced from the left-hand blade ot switch 42, by way ofline 79 through contacts A 50, by Way of line 95 through coil B 71 andcontacts B 68, by way of line 96 through coils P 91 and H 72 andcontacts F 88, by way of line 89 through contacts A 51, to theright-hand blade of switch l2. The purpose of the energization of theseholding coils will be seen from later description. The engagement ofcontacts F short-circuits resistance 2", increasing the voltage appliedto generator field winding portions 17 and 18. Thus the generatorvoltage is brought up to its full value and the motor comes up to fullspeed. Also sufficient current is now supplied to the coil G 75 to causethe operation of the maintaining relay. Thus contacts G 97 engage,by-passing accelerating switch contacts F 88. It is to be understoodthat several accelerating switches may be employed to short-circuitsuccessively sections of resistance 2T, all but one, illustrated asShort-circuiting the whole of the resistance, being omitted in order tosimplify the description.

The starting of the car in the down direction is accomplished in asimilar manner and will be only briefly described. The operator movesthe car switch into position where its contact bar 52 bridges contacts70, 98, 100 and 101. Upon the engagement of the contact bar and Contact98, a circuit is completed for the down direction switch actuating coilC 102 and coil H 58 which circuit may be traced from the left-hand bladeof switch 42, through coil 58, as previously traced, by way of line 103through coil C 102, car switch contacts 98 and 70, by way of line 63through contacts B 05, to the right-hand lade of switch 42 as previouslytraced. The engagement of the contact bar and contact 100 prepares acircuit for coil F 83 and the engagement of the contact bar and contact101 completes a circuit for the coil P 59 by way of line 104. The downdirection switch, upon operation, causes the separation of contacts C 62and the engagement of cont-acts C 105, C 106 and C 107, these contactscorresponding with up direction switch contacts B 65, B 66, B 67 and B68 respectively. The holding coil of the down direction switch isdesignated. C 64. The circuit for coil F 83 is completed by contacts H81 as before. Further than this, the operation of starting the car inthe down direction is the same as described for starting it in the updirection.

Assume that the car is running in the up direction and that the operatorcenters the car switch between the second and third oors in order tostop at the third floor landing. Upon the disengagement of the contactbar 52 and Contact 56, the circuit for the leveling switch motor relayactuating coil P 59 is broken. The relay remains in operated condition,however, due to its holding coil P 91. The disengagement of contact 55and the contact bar breaks the circuit for thev accelerating switchactuating coil F 83. The ac` celerating switch, therefore, drops out,causing the separation of contacts F 88 and F 90 and the engagement ofcontacts F 87. The separation of contacts F 88 is simply' in reparationfor the next starting operation, t ie circuit for coils B 71, P 91 andH72 being maintained by contacts G 9T. The separation of contacts F 90removes the short-circuit for resistance 2T, decreasing the strength ofthe generator field winding portions 1,7 and 18. Thus the generator' E.M. F. is decreased and the speed of the elevator motor is reduced.Discharge resistances 24 and 25 act to smooth out the retardation. Theengagement of contacts F 87 short-circuits the holding coil P 91 of theleveling switch motor relay. The disengagement of contact 54 and contactbar 52 breaks the circuit for actuating coils B 57 and H 58. The updirection switch and brake switch are maintained in operated condition,however, by their holding coils B 71 and H 72 respectively.

The leveling switch motor relay P, dropping out upon ltheshort-eircuiting of coil leveling switch are extended vided for eachfloor.

LR 117. the, left-hand blade of switch 42, by way of P 91, causes theseparation of contacts P 93 to deenergize the leveling switch motor 38.In this manner the opcratin rollers of the or engagement by the levelingcams. Referring to Figure 2, the leveling switch motor is operativelyconnected tothe leveling switch by means of an arm 108 on the motorshaft, a connecting link 110 and a lever 111. In the startingoperation., the motor 38 being energized, arm 108 rotates, actingthrough link 110 and lever 111 to move the leveling switch as a wholeabout a. pivot.` In this manner the leveling switch operating rollers112 and 113 are moved into position where they do not engage theleveling cams 114 and 115 during motion ol theA car, a stop beingprovided to determine the extent of the movement. It is to be understoodthat leveling cams are pro- Tlie leveling switch is pivoted on a bracket116 secured to the car frame. In the stopping operation, upon thedeenergization of the leveling switch motor, a spring (not shown) movesthe lever 111 and ihereforc the leveling switch back into the firstdescribed position with the rollers 112 and 113 extended for engagementby the leveling cams. Each pair of leveling contacts 32, 33, 34 and 35comprises a stationary Contact an-:l a movable contact operated by theengagement of its corresponding roller and leveling cam. `The fast speedcontacts 34 and 35 are arranged to separate before their correspondingslow speed contacts 32 and 33 in the leveling operation. Springs (nowshown) are provided for causing the selniration'olI the contacts of thepairs asthe leveling operation is effected and stops are provided ifordetermining the extent of movement of the rollers as they ride ol` theleveling cams.

It will be assumed that the ear has notv r "ached the landing and thatthe up leveling switch operating roller 112 moves onto the i verticalsurface of up leveling cam 114 before relay7 (if drops out. Referring toFigure 1 and also to Figure 2 where portions of the circuits employedfor leveling are illustrated and where the coils and contacts of the particular switches included are illustrated in their proper associatedrelations, the engagement of leveling switch up slow speed contactslcompletes a circuit for the up leveling direction switch actuating coilLU 78 and the field control leveling relay actuating coil This circuitmay be traced from line 79 through contacts A 50, line 124, levelingswitch contacts 32, by` way of line 125 through coil LU 78 and coil LR117, by Way of line 89 through contacts A 51, to the rightliand blade ofswitch v42.r The engagement of the leveling switch up fast speedcontacts 34 completesthe circuit for fast speed leveling relay actuatingcoil LF 130. This circuit completed.

may be traced from the left-hand blade of switch 42, by way of line 79through contacts A 50, line 124, leveling switch contacts 32, by way ofline 131 through leveling switch contacts 34, by way of line 132 throughcoil LF 130 and resistance 133, to the right-hand blade of switch 42 aspreviously traced. It is to be noted that, due to the fact that thecircuit for coil LF 130 is through leveling switch slow speed contacts32, the circuit for coils LU 78 and LR 117 must be made in or: derthat'the circuit for coil LF 130 may be The field control leveling relayLR, upon operation, causes the engagement of contacts LR 127, LR y134and LR 135. The engagement ofcontacts LR 127 completes a dischargecircuit around the actuating coil ot the relay, the circuit includingdischargeresistance 162 and inductance coil X 126. The engagement ofcontacts LR 134 completes a circuit forthe up direction switch and brakeswitch actuating coils B 57 and H 58 respectively, causing theirreenergization. This circuit may be traced from the left-hand blade ofswitch 42, by way of line 79 through contacts A 50, by way of line 60through coil H 58, coil B 57 and contacts LR 134, by way ofline 89through contacts A 51, to the righthand blade of switch 42. Thereenergization of these coils has no particular eect under the assumedsequence of operation of the switches, however, as the up directionswitch and brake switch are being maintained in o perated condition ,byholding coils B 71 and H 72. The engagement'of contacts LR 135 completesthe circuit for the actuating coil L 136 of the field control switch.This circuit may be traced from the left-hand blade of switch 42, by wayof line 79 through contacts A 50, by way of line 137 through contactsLR135 and coil L 136,`by way of line 89 through contacts A 51, to theright-hand blade of switch 42.

The field control switch L, upon operation, causes the separation ofcontacts L 47. L 120 and L 122 and the engagement of contacts L 140. L141 and L 142. The purpose of contacts L 47 and L 142 willbe seen fromlater description. The separation of contacts L 120 and L 122 breaks thecircuit for portions 17 and 18 of the -generator separately excitedfield winding. The immediate engagement of contacts L 140 and L 141.however, reconnects these portions to the mains. Thepolaritv ofthelatter connection is such that the direction of the flow of currentthrough portion 18 is reversed while the direction of the flow ofVcurrent through winding portion 17 remains the same. As a result of thischange of connections, the magnetizing force due to winding portion 18opposes that'due to wind. ing portionl. .As above set'forth, however,actuating coil LU 78 of the'fup leveling direction switch was energizedupon the engagement ot the levelingswitch slow speed contacts 32. Thisswitch, operating along with relai7 LR, causes the engagement ofcontacts LU 144. Thus, as the field control switch operates to reversethe connections for field winding portion 18, switch LU operates throughits contacts LU 144 to connect a portion of resistance 28 in parallelwith this winding portion so that the current in portion 18 is less thanthat in portion 17. The magnetizing torce due to portion 18, therefore,is less than that due to portion17.

As previouslyr set forth, fast speed leveling rela)1 actuating coil LF130 was energized by the engagement ot up fast speed leveling contacts34. 'l This relay, upon operation, causes vthe separation ot contacts LF145 and the engagement ot contacts LF 146. The purpose .oflcontacts LF145 will be explained later.

The Aengagement of contacts LF 146 shortcircuits a portion ot resistance28. Thus, under the assumedsequence ot operations. the Afast speedleveling relay is effective to determine the amountof resistance 28which is connected across field winding portion 18 b v the engagement otcontacts LU 144, this amount ot resistance being indicated as adjustablesection 147.

The engagement of lield control switch contacts L 142 short-circuits aportion of resistance 27 tor the generator separatelv excited lieldwinding, the amount of resistance in this portion being adjusted to givesatis- `tactorvoperation for the particular installation. .lVithcontacts L 12() and L 122 separated and contacts B 65,13 (i7, L 140, L141, lL 142, LU 144 and vLF 146 in engagement, an E. M. F. is generatedwhich causes thc elevator motor to run at a suitable fast leveling speedinthe up direction as will be seen from later description.

Discharge resistances 24 and 25 act to smooth out not onlv the change ingenerator E. M. F. due to the reinsertion of resistance v27 in circuitwith the field winding but also that due to the above described changein connections tor effecting the leveling operation.

.t is to he noted that the separation ot contacts L 120 and L alsobreaks the circuit tor the actuating coil G "Z of theinaintaining relav.Rela: therefore, d ruppe-fl out touseparate contactsy G 97. breakin@-the circuit tor holding coils B 71 and H fr, ot the up direction switchandthe brake switch re- I spectively, These switches were maintained.

in operated condition, however, b v their actuating coils, theengagement ot contacts LR 4184 causing the reenergization of these coilsas previously explained. Relai-v G is maintained operated atte-rcontacts F 90 separateto remove the short-circuit for resistance 27because of theiiact that the current through its actuating coil issustained br the action of ield winding-portion 17 and dischargercsistance 2l. Thus, even though switch L has not operated to cause theseparation of contacts L 120 and L 122, should the current in themaintaining relay actuating coil (lr 75 decrease to a predeterminedvalue, the relay would drop out. Such operation might result from tooearl;7 centering of the car switch, i. e., the current in coil G 75would decrease to this predetermined value before the operation oit theleveling switch to cause the engagement of its slow speed contacts. As aresult, contacts G 97 would separate to deenergize the up directionswitch and brake switch holding coils B 71 and H 72 respectively. Thismight permit the direction switch and brake switch to drop ont, theiractuating coils having been denergized by the centering' of the carswitch. The engagementot' the slow speed leveling contacts however, asroller 112 rode onto the vertical surface of its leveling cani, wouldcause the engagement ot contacts LR 11S-'L and thus the energization otcoils B 57 and H 58.

The up leveling direction switch LU, upon operation, also caused theengagement of contacts LU 170 and LU 171. The purpose of cont: cts LU170 will be seen troni later description. The engagement of contacts LU171 completed the circuit for actuating coil M 128 ot the series fieldrelay. This circuitmav be traced from the lett-hand blade of switch 42,by wav ot line 79 through contacts A 50, by wa)v of line 172 throughcontacts LU 171` intluctanre coil X 150 and coil M 123, by wav et line89 through contacts A. 51, to the right-hand blade ot switch 42. Theseries lield rela 'v M did notI operate immediately upon the completionot the circuit for actuating coil, its action being delayed bjr thceliect of inductance coil X 150. Relay M, upon operation, causes theengagement of contacts M 151 to complete the circuit for the seriesfield switch actuating coil N 152. This circuit may be traced troni thelett-hand blade ot switch 42, b v wa;v of line 79 through contacts A 50,by wav ot line through coil N and contacts M 151, hv wav ot line 89through contacts A, 51, to the right-hand blade ot switch 42. Switch N,upon operation, causes the separation ot contacts N 154, hreal-:ing thecircuit including resistance 23 in shunt to the. generator series tieldwinding lil. The generator series field coils are so wound that, withoutthe parallel resistance 23, they would have too great an ettect forproper operation of the ear. The desired compounding is obtained byemploying the low resistance shunt. Upon separation of contacts N 154,the strength of the series field is increased for the leveling operationso as to aid in obtaining the desired stopping operation. The shortdelay in the action of relay M, and therefore the switch N, upon theinitiation of the leveling operation, is desirable iii-order that thecurrent in the generator armature-elevator motor armature circuit mayadjust itself to such a value t-hat proper series field strenf'vthduring the levelingoperation may be obtained.

As the car nears the third Hoor landing.l roller 112 rides off thevertical surface onto the obli ue surface of cam 114. This results in te separation yof up fast speed leveling contacts 34, deenergizingactuating coil LF 130 of the fast speed leveling relay. The fast speedleveling relay, upon dropping out, causes the separation of contactsLl!" 146 and the engagement of contacts LF 145. The separation ofcontacts LF 146 removes the short-circuit for section 155 of resistance28, increasing the ohmic value of the resistance shunting generatorfield winding portion 18. Thus the current now supplied to field Windinrportion 18 is increased and that supplied to Windinr portion 17 isdecreased. The generator M. F., therefore, is again lowered and theelevator motor runs at an intermediate leveling speed. T he separationof contacts LF 145, upon the operation of the fast speed leveling relay,prevented the energization of the intermediate speed leveling relayactuating coil LI 156 upon the engagement of up leveling 'directionswitch contacts LU 170. Upon the dropping out ofthe fast speed relay,however, the reengagement of contacts LF 145, completes the circuit forcoil LI 156. This circuit may be traced from the left-hand blade ofswitch 42, by way of line 79 through contacts A 50, by way of line 157through contacts LU 170, inductance coil X 158, coil LI 156 and contactsLF 145, by way of line 89 through contacts A 51, to the right-hand bladeyof switchy 42. The relay LI does notgoperate immediately, however, itsaction bein delayed by the effect of inductance coil 158. It is to benoted that, if the leveling operation is such that the up fastr speedleveling contacts 34 do not engage and therefore the fast speed levelingrelay actuating coil is not energized to cause the separation ofcontacts LF 145, the inductance coil X 158 acts to dew lay the operationof relay LI upon they engagement of contacts LU 170. T ie relay LL uponoperation, causes the separationof contacts LI 160 to remove theshort-circuit for the remaining section 161 of resistance 28, againincreasing the ohmic value of the resistance shunting generator fieldwinding ortion 18. Thus the current supplied to geld winding rtion 18 isincreasedand that supplied to winding ortion 17 is decreased. Thegenerator E.`M. lig., therefore, is still further decreased and theelevator motor runs at its slowest speed.

Shortly before the car reaches an exact level with the landing, theroller 112 rides off the oblique surfacey of cam 114, thereby separatingthe slowv speed leveling, contacts 32. The circuit for coil LU 78 andcoil LR 117 is thus broken. The4 up 'leveling direc-- tion switch yLUdrops out immediately, separating contacts LU 144, LU 170 and LU-171.

f The separationof contacts LUk 171 breaks ythe circuit for coil M 123,relay M droppinfr outto cause theseparation of contacts `l\- '151,breaking the circuit for series field switchcoil N 152. Switch'` N,therefore, drops out to cause the reengagement of its contacts N 154 toreconnect resistance 23 in shunt to the generator series field Winding.The separation of contacts LU 144 disconnectsr resistance 28 from acrossfield winding portion 18, thereby rendering the opposing magnetizingforces exerted by winding portions'17 and 18 equal. As will be seen asthe description proceeds, however, switches B, L and H o erate, asy soonas relay LR drops out, to isconnect the Windingportions from the mainsand toreconnect them for cumulative action tothe generator armature.

Relay LR does notdrop out immediately the circuit 4for itsactuating coilLR 117 is broken, itsaction being delayed by the effect of inductancecoil X 126 and discharge resistance 162. The purpose of the delay in thedropping out' of relay LR will beL seen from later description treatingwith the operation of the system yduring an overrun. Relay LR, upon droping out, causes the separation of contacts R 127, LR 134 and LR 135. Theseparation of contacts LR127 breaks the circuit comprising resistance162 and inductance coil X 126in shunt to coil LR 117. The separation ofcontacts LR 134 breaks the circuit for coils H 58 and B 57. Theseparation of contacts LR 135 breaks the circuit for coil L 136.`v Y

`Upon the circuit for its actuating coil being brokemup direction switchB drops out, causing the separation of contacts B 66, `B 67 and B 68-andthe reengagement of contacts 65. Switch H drops out along with switch B,causing the separation of contacts H andH `81 and the reengagementofcontacts H 77.` Switch L, upon'dropping out, causes the Separation ofcontacts L 140, L 141 and L 142 and the engagement of contacts L 47, L120` and L 122. The separation of contacts 4B 68 opens line 95 includingholding coil B 71, the circuit for coil B 71 and coil H 72khavingalready been broken, however,

by the separation of contacts Gr 97 as preseparationV of contacts L 140and L 141 and the engagement of contacts L 120 and L 122 reconnects thefield winding portions for cumulative action, the field winding beingsimultaneously disconnected from the mains and connected to thegenerator armature, however, by the separation of contacts B 66 and B 67and the engagement of contacts H 77. The separation or contacts H 80breaks the circuit for the brake release coil 30, effecting theapplication of the brake. The polarity ofthe connection of the generatorfield winding to the generator armature is such that the generator sendscurrent through the whole winding in a direction to oppose the iiuxwhich produces the generator E. M. F., thus tending to destroy theresidual fiux of the generator field.

Thus, the brake being applied and the generator separately excited iieldwinding being disconnected from mains 40-41, the car is brought torestlevel with the third floor landing.

In the event of an overrun, assuming in the above example that the caroverruns the third floor to the extent of causing the engagement of downslow speed leveling contacts 33, a circuit is completed for coil LR 117and actuating coil LD 165 of the down leveling direction switch. Thiscircuit may be traced from the left-hand blade of switch 42, by wa y ofline 79 through contacts A 50, line 124, contacts 33, by way of line 166through coil LD 165, by way of line 125 through coil LR 117, bv way ofline 89 through contacts A 51, to the right-hand blade of switch 42. The down leveling direction switch LD, upon operation, causes theengagement of contacts LD 175, LD 176 and LDv 177. As reviouslyexplained, relay LR is maintaine operated after up slow speed levelingswitch contacts 32 separate by the action of inductance coil X 126 anddischarge resistance 162. This portion of the system is adjusted so asto maintain relay LR operatedl during an overrun until the circuit forits actuating coil LR 117 is completed by the engagement of the slowspeed leveling switch contacts for returning the car to the floor, thesecontacts being down slow speed leveling switch contacts 33 in theexample assumed. Thus, upon an overrun into a slow speed leveling zone,contacts LR 134 and LR 135 remain in engagement maintaining the brakeswitch H, up direction switch B and field control switch L operated. Theengagement of down leveling direction switch contacts LD 175, thereore,connects a portion of resistance 28 across ie'ld winding portion 17 sothat the current in winding portion 17 is now less thanthat in windingportion 18. Throughout the leveling operations described for bringingthe car to the floor during an underrun, the current supplied to windingportion' 18 from the mainsY was in' a direction such as to tend to causethe generation of an E. M. F. of a polarity for causing the motor tomove the car in the opposite direction, namely, downwardly. The currentsupplied to Winding portion 17, however, was in the same direction aswas previously supplied to the whole winding before the levelingmechanism took control, thus tending to cause the generation of an E. M.F. of a polarity for causing the motor to continue to move the car inthe same direction. Due to the fact that winding portion 18 was shuntedduring this operation by varying portions of resistance 28, themagnetizing force of winding portion 17 predominated and the E. M. Fgenerated was of proper polarity for causing the car to continueupwardly toward the third floor landing. Upon an overrun, the currentthrough the field winding portions is not reversed due to the operationof the leveling mechanism to effect the return of thel car to the floor,the direction of the current supplied to winding portion 17 remaining inthe direction tending to cause the generation of an EMF. of a polarityfor causing the motor to continue to move the car in the same direction(upwardly) and the direction of the current supplied to winding portion18 remaining in adirection tending to cause the generation of an E. M.F. of a polarity for causing the motor to move the car in the oppositedirection (downwardly). As the engagement of contacts LD 175 places thedesired portion of resistance 28 in shunt to winding portion 17,however, the magnetizing force due to winding portion 18 predominates,causing the generation of an E. M. F. of proper polarity for causing theelevator motor to start the car in the down direction to return to thefloor. As intermediate speed leveling relay contacts LI 160 are inengagement shortcircuitcd section 161 of resistance 28 and as theoperation of the relay to separate these contacts, upon the encrgizationof its actuating coil Ll 156 by the engagement of contacts LD 176, isdelayed by the effect of inductance coil X 158, the generation ofsuflicient voltage to cause the elevator motor to start the car upon itsreturn movement to the landing is assured.

The engagement of contacts LD 177, arranged in parallel with up levelingdirection switch contacts LU 171, completes the circuit for series fieldrelay actuating coil M 123. As before, the operation of relay M isdelayed by the effect of inductance coil X 150. Thus contacts N 154,depending for their separation upon the operation of relay M, remainclosed momentarily to insure that the current in the generator'armature-motor arma ture circuit has fallen to a low value. Since thecurrent in the series field winding may be flowing in a direction suolias to cause the generation of an E. which is of proper llif) clarity foroperating the car in the down irection, immediate increase in thestrengthy of the series ield might result in the car again being carriedpast the floor. As` the car returns to the floor, it is stopped by theseparation of slow speed leveling contacts 33 in a manner similar tothat described for approaching the floor in the up direction.

If the overrun is great enough to cause the engagement of the levelingswitch down fast speed contacts 35 as `well as the levelin switch downslow speed contacts 33, coil L 130 is energized.v As before, relay LFcauses the engagements of contacts LF 146 to shortcircuit sections 155and 161 of vresistance 28, increasing the generator vvoltage andfcausingthe elevator motor to run at its fast leveling speed. Also contacts LF145 separate to prevent the energization of intermediate speed levelingrelay actuatin coil LI 156 by the engagement of contacts D 176. Furtherthan this, the operation on an overrun is as above described.

The operation of the system is somewhat modified in the event that astop is to be made when the car is moving downwardly. In order tobriefly describe the Operation, assume that the sto'ming operation hasprogressed to the extent that the levelin switch operating rollers havebeen extende for engagement by the leveling cams and that down roller113 moves onto the vertical surface of down cam 115 before relay G dropsout. The engagement of the leveling switch down slow speed contacts 33completes the circuit, previously traced, for down leveling directionswitch coil LD 165 and field control leveling relay coil LR 117. RelayLR causes the engagement of contacts LR 134 completing the circuit forup direction switch actuatin coil B 57 and brake switch actuating coil58 and the engagement of contacts LR 135 completing the circuit for `thefield control switch coil L 136, these circuits having been previouslytraced. Theenergization of coil H 58 is to maintain switch H operatedupon the deenergization of its holding coil H 72. Down direction switchC being maintained in operated condition by itsliolding coil C 64, thedirection switch mechanical interlock acts to prevent the operation ofthe up direction switch B in res onse to the energization of coil B 57unti the down direction switch drops out. Switch L, as before, operatesto reverse the connections for field winding portion 18, the separationof contacts L 120 and L 122 breaking the circuit for coil G7 5 of themaintaining relay. Relay G, therefore, drops out, separating itscontacts G 97 to break thecircuit for the L engagement of contacts B 66and B 67.

Thus the connection for the whole field wind ing is reversed yso thatthe net result of the operation of switches L, C and B is that thedirection of the flow of current through winding portion 17 is reversedwhile the iow of current through winding portion 18 remains the same.Thus the lnagnetizing force due to winding portion 17 opposes that dueto winding portion 18. As set forth above, however, actuating coil LD165 of the down leveling direction switch was energized `upon theengagement ofthe leveling switch slow seed contacts 33. This switch,operating speed contacts 33, causes the operation of the n fast speedleveling relay. As previously eX- plained, the fast speed levelingrelay, by means of its contacts LF 146, causes all of resistancek 28except section 147 to be shortcircuited. Also field control switchcontacts L 142 short-circuit the selected portion of resistance 27. Asin the case where the car wasl brought tothe landing upon an underrun inthe up direction, with contacts L 120 and L 122 separated and contacts B66, B 67, L 140, L 141, L 142, LD 175 and LF 146 in engagement, an E. M.F. is generated which causes the elevator motor to run at a suitablefast leveling speed in the down direction.

It is believed that the remainder of the operation of bringing the carto the landing will be obvious from the description of bringing it tothe landing upon an underrun when moving in the up direction. Should thecar be carried past the landing, when moving in the down direction,resistance 28 is connected in parallel with field winding portion 18,causing the car to be returned to the landing. It is to be understoodthat the operator may control both the acceleration and retardation ofthecarY by moving the car switch in steps. Should the operator suddenlymove the car switch from one position into thek other,kfor example fromup into down positionV injury to the system is prevented b vcontacts B65 which remain separated until the up direction switch drops out. Fieldcontrol switch contacts L 47, arranged in the circuit for the actuatingcoil F 83 of the accelerating switch, prevent the operation ofi theaccelerating switch during the leveling period.

During the leveling period, in systems such as those in which thegenerator separately excited lield winding is connected to the source inthe same manner during leveling as during car switch operation with thedesired `low values of generator E. M. F. for leveling obtained bypermitting only a small amount of current to low through the winding,were the same values of current supplied to the winding for bringing thecar to the Hoor upon an underrun as for returning the car to the floorafter an overrun, variations in operation might 'occur due to thevarying eftects of the residual iiuX of the generator ield. As suchsmall values of current effect the production of low values of lux, theresidual flux presentwould form a large percentage of the total flux andtherefore might atleet the operation of the system very markedly. Inorder that the effects of the residual tlux may be clearly seen,reference may be had to the assumed hysteresis curve shown in Figure 3.This ligure illustrates the conditions when a small current is suppliedto the separately excited held winding of a generator, as during theleveling operation. The magnetizing forces due to this small current arerepresented as NI and n-NL depending on whether the car is approachingthe floor, or returning to the floor after an overrun. Assume that thegenerator armature E. M. F. has been of a value V1 and that later, inattempting to make a landing, the self-leveling operation takes placewith the car approaching the floor. The E. M. F. of the generator duringthis period will be of a value V2. On the other hand, it the caroverruns the floor, the E. M. F. of the generator for returning the carto the floor will be of a value V3, which value is much less than thevalue V2. Hence the speed of the elevator motor is much less. The valuesV2 and V3 of the generator E. M. F. may vary during operation of thesystem depending upon the previous magnetic state of the machine.Obviously, such diilerences in the numerical values of the E. M. F.generated would result in undesirable variations in operation underleveling conditions. These variations cannot be satisfactorily correctedmerely by adjusting the amount of resistance in series with theseparately excited ield winding. For example, if the amount ofresistance were decreased in order to raise the value of V3, the valueV2 also would be increased, resulting in an increasing tendency to runpast the floor. Similarly. if the amount ot resistance were increased inorder to lower the value of V2, the value of V3 also would be lowered,which value might be too low to effect the return of the car to thefloor after an overrun. It the effects of residual flux are eliminatedfor leveling operating conditions, the system may be adjusted so as toobtain more uniform operation. This desired result may be attained byreversing the polarity of certain of the field poles. The

preferred arrangement for effecting this change has already beendescribed in connection with Figures 1 and 2, the particular arrangementof the separatel excited field winding being illustrated in igure 2.

Referring to Figure 2, it is preferred to group the coils for the northand south poles N and S together to form the portion 17 and those fort-he north and south poles hl1 and S1 together to form the portion 18.The coils forming the portion 17 are connected in series relation as arethose forming the portion 18. For convenience of explaining the actionof portions 17 and 18 of the field winding, assume again that the car ismoving in the up direction. With switch L in deenergized position, asduring car switch operation, the current flows through the eld coils insuch manner as to provide oles of alternate polarity as indicated. ponan underrun in sto ping, the up main direction switch contacts 66 and B67 remain in engagement and switch L operates to cause the separation ofcontacts L 120 and L 122 and the engagement of contacts L 140 and L 141.Thus, as previously described, although the direction of the flow ofcurrent through the coils for poles N and S (winding portion 17) is notaii'ected, the current through the coils for poles N1 and S1 (Windingportion 18) is reversed. Thus N1 becomes a south pole and S1 becomes anorth pole. Similarly, upon an underrun in stopping, where the car hasbeen moving in the down direction during car switch operation, the downmain direction switch drops out and the up main direction switch B andfield control switch L operate to cause the separation of contacts L 120and L 122 and the engagement of contacts B 66, B 67, L 140 and L 141.Thus the net result, as previously explained, is to cause the current toflow in the same direction through the coils for poles Nl and S1(winding portion 18) but to reverse the flow of current through thecoils Jfor poles N and S (Winding portion 17 Thus N becomes a south poleand S becomes a north pole. If these poles were excited equally with thewinding connected for the leveling operation, the value of the total E.M. F. at the generator brushes 19 would be substantially zero, since thevoltage generated in part of the generator armature winding would bebalanced out by a voltage of equal value but opposite polarity generatedin the remainder of the winding. However, as previously explained, adifference in the values of the magnetizing forces due to the windingportions is obtained by connecting resistance 28 in parallel with one ofthe Winding portions so that an E. M. F. at the generator brushes isobtained. .By utilizing a large magnetizing force for each pole and byemploying a resistance 28 of such ohmic value as will cause a properdifference in the values of these magnetizing forces, an

cuited so that large magnetizing forces arev still emplo ed for thepoles, the generation of an E. F. for returning the car to the floor, aspreviously explained, being obtained by disconnecting resistance 28 fromone wind'- ing portion and connecting it in parallel with the other. Inthis manner, the iron ofthe various'parts'of the magnetic circuit of thegenerator ield structure is worked on the high ortions ofthe hysteresisloop where the e ect of residual flux is practically nil, and E. M. F.smay be obtained, during leveling operations, the values of which are notaffected by residual flux and are practicallyl the same Whether the carunderruns or overruns the landing. f

The series field winding 16 acts to assist the separately excited eldWinding portions to obtain the desired conditions during operation.Under normal car switch operation,

when these Winding portions assist each other,

the series field winding acts in the usual manner to compensate forvarying load conditions. During leveling conditions, when the elevatormotor is lifting a load, the eect of the series field winding is to aidin. bring ing the car to the floor since the` current flow in the seriesfield winding is in `such direction as toproduce a magnetizing vforcewhich assists thatdue to the field winding portion through whichthespredominating current flows and opposes that due to the fieldwinding portion through whichy less current flows. Conversely, wheny theelevator motor is lowering a load, the effect of the series fieldwinding is to aid inl causing the car to stop at the floor since thecurrent flow in the series lield winding is in such direction as toproduce a magnetizing force which op,- poses that due to the fieldwinding portion through which the predominatingr current flows andassists that due tothe field winding portion through which less currentflows.

As previously explained, upon an overrun,

i the up main directionswitch contacts B 66 and i' to the other to eectthe generation of an E. M. F. for returning the car totheiloor.A simplycauses a reapportionment ofthe amount of current supplied'to eachWinding portion. For convenience of explanation, as.-v sume that the carhas been` moving in theup direction vand that it overruns the desiredlanding in stopping. During the part of the leveling period that the caris below the ioor, resistance 28 is connected in parallel with windingportion 18 causing the current supplied to Winding portion 18 to be lessthan that supplied to winding portion 17. The transfer of resistance 28causes the current in winding portiony l8'to be increased and that inwinding portion 17 tobe decreased to the extent that current in windingportion 17 becomes less than that inwinding portionv 18. Thus,considering the generator E. M. F. due to the separately excited fieldwinding, the v)Liredominating voltage generated in one portion of thegenerator armature winding decreases and the opposing voltage generatedin the remaining portion of the armature winding increases with theresult that the so termed opposing voltage is caused to pre- .i

dominate and an E. M. F. at the generator brushes is obtained forcausing thecar to be returned to the ioor.y Due to the fact, however,that the current in one winding portion is. simply decreased while thatin the other is increased, the change in the values of the opposingmagnetizing forces of the winding portions occurs very quickly.Consequently, the change in the relative values of the opposing voltagesgenerated in the generator armature winding portions and therefore t-heestablishment of a generated E. M. F. suitable for returning the car tothe {ioor upon an yoverrun also occurs quickly. Thus the time .requiredto return the car to the desired landing in the event of an overrun ismini mizedy with the result that the overall operating eiiciency ofthesystem as a whole is raised considerably.

It is to be understood that the above described arrangement is suitablefor use with various types of generators and that these generators maybe of other pole numbers. a four pole generator being chosen merely forconvenience o description. It is further to be understoodl that theportions of the field Windingmay be arranged in different circuitrelations and that the coils may be grouped differently to effect thedesired result.

As many changes could be made ink the above construction and manyapparenly widely different embodiments of this invention couldy be madewithout departing from the scope thereof, it isvintended that all matandmeans for causing the motor to level the 3f car with a desired landingin stopping7 regardless of whether it underruns or overruns saidlanding, said means comprisin means for connecting said winding to saisource in such manner that the E. M. F. generated due to the fluxcreated by the current flowing in a portion of the winding opposes thatgenerated due to the flux created by the current flowing in theremainder of the winding, means for causing the first mentioned flux tobe less than the second mentioned flux to cause the generation of atotal E. M. F. f proper polarity for bringing the car to the landingduring an underrun in one direction and for returning the car to thelanding after an overrun in the other direction, and means for causingthe second mentioned flux to be lessl th an the first mentioned flux tocause the gene 'ation of a total E. M. F. of proper polarity forbringing the car to the landing during an underrun in said otherdirection and returning the car to the landing after an overrun in saidone direction.

2. In combination an elevator car; a hoisting motor therefor; agenerator for supplying current to said motor, said generator having afield winding; a. source of current; means for connecting the whole ofsaid wind ing to said source to cause the generation of an E. M. F. ofcertain value for causing the motor to move the car 'between landings;and means for causing the motor to level the car with a desired landingin stopping from one direction, regardless of Whether it underruns oroverruns the landing, said last named means comprising means forreversing the connections for a portion of said winding, a resistance,and means for connecting said resistance in parallel with the reversedportion of said winding during an underrun and in parallel with theremaining portion of said winding during the return of the car to thelanding after an overrun.

8. In combination; an elevator car; a hoisting motor therefor; agenerator for supplying current to said motor, said generator having afield Winding divided into two portions; a source of current; means forconnecting the whole of said winding to said source so as to cause saidportions to act cumulatively to obtain a terminal E. M. F. of certainvalue for causing the motor to move the car between landings; and meansfor causing the motor to level the car with a desired landing instopping, regardless of whether it underruns or overruns the landing,said last named means comprising means for reconnecting the whole ofsaid winding to said source so as to cause said portionsl to act inopposition, a resistance, means for connecting a portion of saidresistance in parallel with one of said winding portions to obtain aterminal E. M. F. of a lower value than said certain ie and of properpolarity for bringing the' to the landing upon an underrun in one n beidirection and for returning the car to the landing after an overrun inthe other direction and for connecting said portion of said resistancein parallel with the other winding portion to obtain a terminal E. M. F.of a lower value than said certain value and of proper polarity forbringing the car to the landing upon an underrun in said other directionand for returning the carto the landing after an overrun in said onedirection, and means for increasing the amount of said resistance soconnected, during underruns in either direction and the returning of thecar after overruns in either direction, as the car nears the landing.

4. In combination; an elevator car; a hoisting motor therefor; agenerator for supplying current to said motor, said generator having afield Winding; a source of current; and means for causing said motor tobring the car to a stop at a desired landing, said means comprisingmeans for connecting said winding to said source in such manner that theE. M. F. generated due to the flux created by the current supplied to aportion of said winding opposes the E. M. F. generated due to the fluxcreated by the current supplied to the remainder of said winding, meansfor causing the first mentioned flux to be less than the secondmentioned flux to cause the generation of a total E. M. F. of a certainvalue to cause the motor to run at a certain speed, and means forincreasing the first mentioned flux and for decreasing the secondmentioned flux as the car nears the landing to decrease the total E.M.F. and therefore the speed of the motor.

5. In combination; an elevator car; a hoisting motor therefor; agenerator for supplying current to said motor7 said generator having afield winding; a source of current; means for connecting ysaid windingto said source to cause the motor to run at a certain speed; means fordecreasing the speed of said motor, said second named means comprisingmeans for reversing the connections for a portion of said Winding, aresistance, and means for connecting aportion of said resistance inparallel with said reversed por-y tion of the winding; and means forfurther decreasing the speed of said motor, said last named meanscomprising means for increasing the amount of said resistance soconnected.

6. In combination; an elevator car; leveling mechanism for said car,said mechanism comprising fast speed contacts and slow speed contacts;and means responsive to the engagement of said fast speed contacts forcausing the car to run at a fast leveling speed' and responsive to theseparation of said fast speed contacts, with the slow speed contacts inengagement, for causing the car to run at a speed which is intermediatethe fast and slow leveling speeds and thereafter, upon the expiration ofa predetermined time interval after the separation of said fast s dcontacts, for causing the car to run at s ow leveling speed.

In combination; an elevator car; a hoisting motor for said car; a sourceof current for said motor; means adapted to vary the voltage applied tosaid motor from said source; means for causin Said motor to operate thecar between lan ings, said Second named means comprising means forcontrolling said volt e varying means to control the speed of t e motor;and means for causing the motor to level the car with a desired landingin stop ing, said last named means comprising leve ing mechanism havinfast speed leveling contacts and slow Spee leveling contacts, meansresponsive to the engagement of the fast speed contacts and the slowspeed contacts for controlling said volt-k age varying means to causethe motor to operate the car at a fast levelin speed and responsive tothe separation o the fast speed leveling contacts for controlling saidvoltage varying means to cause the motor to operate the car at anintermediate leveling speed, and means responsive to the separationings, said means comprising a switch operable from one position toanother to cause current to be supplied from said source through saidwinding in one direction to cause said generator to apply voltage tosaid motor ofy a polarity to cause movement of said car in a certaindirection, and a second switch operable from one position to another tocause current to be supplied from said source through said winding inthe other direction to cause said generator to apply voltage to saidmotor of, opposite po arlty to cause movement of said car in theopposite direction; and means for causing the car to be brought to alevel with a landing in stopping, said leveling means `comprising meansoperable, regardless of whether the car underruns or overruns thelanding, to cause the reconnection of said winding to said source insuch manner that the current through the winding for only'half of theenerator pole pieces is reversed to cause the rst named switch to bemaintained in its other position in the event that the car has beentraveling in said certain direction and to cause the return of thesecond switch to its one position and the operation of the first namedswitch from its one to its other posif tion in the event that the carhas been travelname to this specification.

ANTHONY PINTO.

